Troy Sternberg

A three-step floating catchment area method for analyzing spatial access to health services

Gravity-based spatial access models have been widely used to estimate spatial access to healthcare services in an attempt to capture the interaction of various factors. However, these models are inadequate in informing health resource allocation work due to their inappropriate assumption of healthcare demand. For the purpose of effective healthcare resource planning, this article proposes a three-step floating catchment area (3SFCA) method to minimize the healthcare-demand overestimation problem. Specifically, a spatial impedance-based competition scheme is incorporated into the enhanced two-step floating catchment area (E2SFCA) method to account for a reasonable model of healthcare supply and demand. A case study of spatial access to primary care physicians along the Austin–San Antonio corridor area in central Texas showed that the proposed method effectively minimizes the overestimation of healthcare demand and reflects a more balanced geographic pattern of spatial access than E2SFCA. In addition, by using an adjusted spatial access index, the 3SFCA method indicates strong potential for identifying health professional shortage areas. The study concludes that 3SFCA is a promising method to provide health professionals and decision makers with useful healthcare accessibility information.

Tracking desertification on the Mongolian steppe through NDVI and field-survey data

Abstract Changing environmental and socio-economic conditions make land degradation, a major concern in Central and East Asia. Globally satellite imagery, particularly Normalized Difference Vegetation Index (NDVI) data, has proved an effective tool for monitoring land cover change. This study examines 33 grassland water points using vegetation field studies and remote sensing techniques to track desertification on the Mongolian plateau. Findings established a significant correlation between same-year field observation (line transects) and NDVI data, enabling an historical land cover perspective to be developed from 1998 to 2006. Results show variable land cover patterns in Mongolia with a 16% decrease in plant density over the time period. Decline in cover identified by NDVI suggests degradation; however, continued annual fluctuation indicates desertification – irreversible land cover change – has not occurred. Further, in situ data documenting greater cover near water points implies livestock overgrazing is not causing degradation at water sources. In combination of the two research methods – remote sensing and field surveys – strengthen findings and provide an effective way to track desertification in dryland regions.

Performance comparison of LUR and OK in PM2.5 concentration mapping: a multidimensional perspective

Methods of Land Use Regression (LUR) modeling and Ordinary Kriging (OK) interpolation have been widely used to offset the shortcomings of PM2.5 data observed at sparse monitoring sites. However, traditional point-based performance evaluation strategy for these methods remains stagnant, which could cause unreasonable mapping results. To address this challenge, this study employs ‘information entropy’, an area-based statistic, along with traditional point-based statistics (e.g. error rate, RMSE) to evaluate the performance of LUR model and OK interpolation in mapping PM2.5 concentrations in Houston from a multidimensional perspective. The point-based validation reveals significant differences between LUR and OK at different test sites despite the similar end-result accuracy (e.g. error rate 6.13% vs. 7.01%). Meanwhile, the area-based validation demonstrates that the PM2.5 concentrations simulated by the LUR model exhibits more detailed variations than those interpolated by the OK method (i.e. information entropy, 7.79 vs. 3.63). Results suggest that LUR modeling could better refine the spatial distribution scenario of PM2.5 concentrations compared to OK interpolation. The significance of this study primarily lies in promoting the integration of point- and area-based statistics for model performance evaluation in air pollution mapping.

Monitoring the source of trans-national dust storms in north east Asia

Abstract The vast expanse of the Gobi desert across the Mongolian plateau experiences frequent dust storms. In this isolated region remote sensing techniques can provide an effective measurement of dust storms. Brightness temperature channels 4, 5 of AVHRR/NOAA satellite data, emissive bands of MODIS/TERRA satellite data and meteorological station measurement data were used and tested for dust and sandstorm mapping in the desert area of Mongolia and northern China. The differences between thermal bands in combination with geographic information system (GIS) layers were used for mapping in this study. The results show that dust and sand storm maps can be achieved from emissive bands for monitoring of dust and sandstorms. Most active dust storm sources can occur in truly remote areas where there is little or no human activity, although many sources are associated with areas where human impacts are well documented. Thus, on a regional scale dust mobilisation appears to be dominated by natural sources.

Explaining spatial variations in climate hazard impacts in western Mongolia

The winter of 2009/2010 induced a mass loss of livestock known as dzud in Mongolia. We examine spatial heterogeneity in this livestock loss in a western Mongolian province using a semi-structured questionnaire, key informant interviews, meteorological station data, and two datasets derived from satellite imagery. We identify marked local variability in the impact of winter 2009/2010 demonstrated by a striking difference in livestock mortality between three Altai mountain districts and three Gobi desert districts. We explain this pattern with reference to site-specific circumstances. We ascertain a counter-intuitive pattern of milder winters with less snow in Mountain districts when compared to Desert districts, a contrast that was particularly acute in the winter of 2009/2010 which was uncommonly long and hard, with particularly deep and widespread snow cover in the Desert, but unusually mild in the Mountains. Examination of possible drivers of dzud vulnerability at the household and community levels—wealth and herder experience—found virtually no influence on livestock losses, although a large majority of herder households were characterised by a general lack of alternative income opportunities. The severity of conditions undermined many Desert herders’ coping and adaptive strategies, including communal pooling, although those who managed to move their herds in response to the 2009/2010 dzud suffered markedly smaller livestock losses. Limited government capacity, partly influenced by remoteness, further increased vulnerability in the Desert districts where the deep snow restricted access to dzud relief assistance. Implications for hazard management and governance are discussed, as are recent policy initiatives.

Water megaprojects in deserts and drylands

Water megaprojects reconfigure the conception and use of desert landscapes. Driven by limited water resources, increasing demand and growing populations, projects are framed by statements of water delivered, end-users served and local benefits. Decision-making processes, socio-economic costs and environmental implications receive less attention. Research examines the motivations involved and evaluates the challenges of water megaprojects in deserts, including the Great Manmade River (Libya), the South-to-North Water Transfer Scheme (China), the Central Arizona Project (United States) and the Greater Anatolia Project (Turkey), and assesses related projects exemplifying the diversity of water projects in drylands. Their viability and efficacy depends on human motivations and interpretations.

Is Ivy Good or Bad for Historic Walls

Abstract Ivy is often blamed for damaging masonry walls and seen as something that should be removed wherever possible. However, under some circumstances the positive benefits of ivy can outweigh any deteriorative effects. This paper reports on findings from a three-year research project, commissioned by English Heritage, and their implications for managing ivy on historic masonry walls. From field monitoring at a range of sites in England, it was found that ivy provides a thermal blanket for walls, protecting them from extremes of heat and cold and fluctuations in relative humidity. Similarly, studies in and around Oxford show that ivy can minimize particulate pollution reaching walls. Field experiments in Oxford also reveal that ivy rootlets adhering to stone generally only create minor (if any) damage to the stone surface. However, it was also found that ivy can penetrate existing voids and cause damage. A balanced appraisal should inform decisions to remove, leave or even plant ivy. If ivy is allowed to grow on walls, regular and careful maintenance and monitoring are essential.

Contraction of the Gobi Desert, 2000-2012

Abstract: Deserts are critical environments because they cover 41% of the world’s land surface and are home to 2 billion residents. As highly dynamic biomes desert expansion and contraction is influenced by climate and anthropogenic factors with variability being a key part of the desertification debate across dryland regions. Evaluating a major world desert, the Gobi in East Asia, with high resolution satellite data and the meteorologically-derived Aridity Index from 2000 to 2012 id entified a recent contraction of the Gobi. The fluctuation in area, primarily driven by precipitation, is at odds with numerous reports of human-induced desertification in Mongolia and China. There are striking parallels between the vagueness in defining the Gobi and the imprecision and controversy surrounding the Sahara desert’s southern boundary in the 1980s and 1990s. Improved boundary definition has implications for understanding desert “greening” and “brown ing”, human action and land use, ecological productivity and changing climate parameters in the region. The Gobi’s average area of 2.3 million km

Transboundary hazard risk: the Gobi desert paradigm

Transboundary hazard risk reflects how different societies interact with disaster in a shared landscape. In the Gobi desert of northern China and southern Mongolia recurring drought, extreme cold, wind and dust storms are the dominant hazards yet disasters vary significantly in the two countries. Research examined national approaches to environmental engagement and livelihoods in the desert through an assessment of disaster risk in two Gobi communities; farmers in Gansu Province, China, and herders in Dundgov and Omnogov Provinces, Mongolia. Exposure and resilience was evaluated and work examined how risk factors are shaped by policy, economics, culture and social memory. Comparison between two state systems reveals how disaster risk and vulnerability are shaped as much by human action as by the physical climatic event. China stressed government-led disaster management whilst Mongolia emphasised adaptation to hazards. Integrating multiple divisions within a hazard zone is essential to address risk reduction; without this disaster mitigation remains state-specific and lacks applicability to a wider area or global context.

Desert Dust and Health: A Central Asian Review and Steppe Case Study

In Asian deserts environmental and anthropomorphic dust is a significant health risk to rural populations. Natural sources in dry landscapes are exacerbated by human activities that increase the vulnerability to dust and dust-borne disease vectors. Today in Central and Inner Asian drylands, agriculture, mining, and rapid development contribute to dust generation and community exposure. Thorough review of limited dust investigation in the region implies but does not quantify health risks. Anthropogenic sources, such as the drying of the Aral Sea, highlight the shifting dust dynamics across the Central EurAsian steppe. In the Gobi Desert, our case study in Khanbogd, Mongolia addressed large-scale mining’s potential dust risk to the health of the local population. Dust traps showed variable exposure to particulates among herder households and town residents; dust density distribution indicated that sources beyond the mine need to be considered when identifying particulate sources. Research suggests that atmospheric dust from multiple causes may enhance human particulate exposure. Greater awareness of dust in greater Central Asia reflects community concern about related health implications. Future human well-being in the region will require more thorough information on dust emissions in the changing environment.